Excluding and restoring observations with zoom

[dbenn]

@BradWalter reported this in the latest CHOICE course:

Load Alf Ori data for all dates. Zoom way in and exclude the Observation at 2413260.5 with the plot pane open. With the plot pane still open undo the observation exclusion. there are a lot of stars in the field that weren't there before. Now swipe to zoom all the way out and zoom back in close to the same FOV as when the exclusion was made. The extra stars are gone.
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I discovered that the issue has to do with display of discrepant points. The additional points that appear are discrepant points that are excluded by default when you load a dataset. When you exclude the observation the discrepant points appear for some reason. If you zoom all the way out with an upward-left swipe the discrepant points disappear as you can verify by zooming in again. If you click the zoom out button instead of swiping, the discrepant points do not disappear. If you zoom back in after swiping out to the full dataset view and undo the exclusion, the discrepant points reappear. If, however, you undo the exclusion when you are zoomed all the way out by swiping, all discrepant points appear for an instant and then disappear.

I reloaded the data set as before with all times selected. I zoomed in around this same point with approx the same view limits as before and turned on discrepant points in the plot control window. Discrepant points appeared and the view expanded somewhat in the vertical direction. When I deselected discrepant points The window returned to the vertical limits before discrepant points were added to the plot, but the discrepant points were not removed from the plot. I had to zoom all the way out by swiping to remove them. They were not removed when I clicked on the zoom out button. This may indicate that there is a broader issue with the display of discrepant points.